The International Journal of Neuropsychopharmacology

Research Article

Can transcranial direct current stimulation enhance outcomes from cognitive training? A randomized controlled trial in healthy participants

Donel M. Martina1a2, Rose Liua2, Angelo Alonzoa1a2, Melissa Greena3, Michael J. Playera1a2, Perminder Sachdeva4a5 and Colleen K. Looa1a2a6 c1

a1 Black Dog Institute, Sydney, Australia

a2 School of Psychiatry, University of New South Wales, Sydney, Australia

a3 Research Unit for Schizophrenia Epidemiology, School of Psychiatry, University of New South Wales, Sydney, Australia

a4 Centre for Healthy Brain Ageing (CHeBA), School of Psychiatry, University of New South Wales, Sydney, Australia

a5 Neuropsychiatric Institute, Prince of Wales Hospital, Sydney, Australia

a6 St George Hospital, South Eastern Sydney Health, Sydney, Australia

Abstract

Computer-administered cognitive training (CT) tasks are a common component of cognitive remediation treatments. There is growing evidence that transcranial direct current stimulation (tDCS), when given during cognitive tasks, improves performance. This randomized, controlled trial explored the potential synergistic effects of CT combined with tDCS in healthy participants. Altogether, 60 healthy participants were randomized to receive either active or sham tDCS administered during training on an adaptive CT task (dual n-back task), or tDCS alone, over 10 daily sessions. Cognitive testing (working memory, processing speed, executive function, reaction time) was conducted at baseline, end of the 10 sessions, and at 4-wk follow-up to examine potential transfer effects to non-trained tasks. Altogether, 54 participants completed the study. Over the 10 ‘online’ sessions, participants in the active tDCS+CT condition performed more accurately on the CT task than participants who received sham tDCS+CT. The performance enhancing effect, however, was present only during tDCS and did not result in greater learning (i.e. improvement over sessions) on the CT task. These results confirm prior reports of enhancement of cognitive function during tDCS stimulation. At follow-up, the active tDCS+CT group, but not the sham tDCS+CT group, showed greater gains on a non-trained test of attention and working memory than the tDCS-only group (p < 0.01). Although this gain can mainly be attributable to training, this result suggests that active tDCS may have a role in further enhancing outcomes.

(Received November 26 2012)

(Reviewed January 11 2013)

(Revised March 22 2013)

(Accepted April 19 2013)

(Online publication May 30 2013)

Key words

  • Cognition;
  • cognitive training;
  • direct current stimulation;
  • healthy;
  • working memory

Correspondence

c1 Address for correspondence: Professor C. Loo, Black Dog Institute, Prince of Wales Hospital, Barker St, Randwick. 2031, Australia. Tel.: 61 2 9382 3721 Fax: 61 2 9382 8208 Email: colleen.loo@unsw.edu.au